Yes, In My Backyard

Localities and States Push for Wider Acceptance of Accessory Dwelling Units

Photo courtesy of Rambo Halpern

Aging parents who want to maintain a level of independence. Young adults who can’t find an affordable place to live. A person with disabilities who benefits from family support but also seeks autonomy.

What if there was a simple solution to help communities
struggling with high housing costs, limited developable land, and a demand for
multigenerational living?

An increasing number of communities around the U.S. have
found that there is such a solution: accessory dwelling units (ADUs). Also
called an in-law suite, granny flat, or secondary dwelling unit, an ADU offers an
additional self-contained living unit that
typically has its own kitchen, bedroom(s), and bathroom space, while
maintaining independence and privacy from the primary home.

ADUs can take many forms: a second small backyard cottage on the same grounds as (or attached to) a single-family house, an apartment over the garage, or a basement apartment. They offer a relatively inexpensive means to provide more affordable housing options in a neighborhood without changing neighborhood character. ADUs have the added appeal of generally not needing new infrastructure or public investment, and not contributing to a concentrated increase in density. And in addition to providing additional space for family members, an ADU may also serve as a rental unit, providing additional income for the homeowner.

The New Hampshire law prohibits communities from requiring that the units have fewer than two bedrooms, be smaller than 750-square-feet, or that a person related to the owner live in the ADU. However, towns and cities may require that one of the units is owner-occupied. Local municipalities also have oversight over parking requirements, and can limit ADUs to one per home and institute design guidelines.

San Francisco Ups the Ante

In addition to the statewide support for ADUs, San Francisco—in one of the most expensive housing markets nationwide—has pioneered the capacity to carve ADUs out of existing apartment buildings. New units are being created out of garages, storage spaces, even vacant boiler rooms.

San Francisco’s regulatory innovations have helped to add hundreds
of new ADUs to the pipeline since 2017. The keys to success of San Francisco’s
ADU regulations includefast-tracking
plan reviews, adding flexibility to city guidelines, and cultivating lender and
industry support. Such measures would easily help encourage the
development of ADUs elsewhere, too.

Twin Cities, But Separate Paths for ADUs

Over the last five years, both of the Twin Cities have
explored how to increase housing diversity and add density in residential
neighborhoods.

In 2014, Minneapolis introduced an ordinance to allow all
types of ADUs—internal, attached and detached—to be built on single- and
two-family lots throughout the City. The only requirement was administrative
review for compliance. The initiative yielded quick interest, and in the first
three years, building permits were issued for 92 ADUs.

In 2013, St. Paul undertook a more incremental,
neighborhood-based approach to pilot ADUs in particular neighborhoods near the
Green Line light rail. After extensive public input and review, a 2016
ordinance established the total area permitted for ADUs in an area of just 3.5
square miles—a half mile on either side of a segment of the light rail
corridor. However, St. Paul’s piecemeal approach appeared likely to result in allowing
ADUs in one neighborhood but prohibit them just a few blocks away. In 2017,
only one ADU was permitted for construction.

Major points of discussion on ADUs in St. Paul included a preference that primary properties be owner-occupied and how the units would be inspected. Finally, in 2018, the St. Paul City Council voted to allow Accessory Dwelling Units (ADUs) on single-family lots throughout the city.

Sparking a Specialty Line for Architects

Now that you can get a building permit to add an in-law
suite, how do you actually construct it? After all, though it is intended to be
an independent living space, the scale is much different than a typical
single-family home. Fortunately, some architects are focusing on accessory
units as a new business opportunity.

Shortly after Minneapolis adopted their ADU ordinance in
2014, architect Christopher Strom launched Second Suite, a design service
specializing in ADUs that allows city residents to expand without increasing
the mass of the primary residence. The Minneapolis ordinance limits ADUs to a
total of 1,000 square feet, including parking. Architects specializing in ADUs benefit
from design options that are not only freestanding. With one accessory building
allowed per property, many homeowners with a detached garage add a second story
to house an ADU.

Sidekick Homes, based in Denver, Colorado, specializes in producing ADUs with universal design (UD), accessible features, and sustainable design that can be placed on single-family lots adjacent to existing homes or used as new construction. Sidekick Homes was founded by architect Mike Kephart, recently inducted into the Best in American Living Awards™ (BALA) Hall of Fame. The Hall of Fame awards recognize innovative, well-respected individuals and companies in the building industry who have significantly affected residential design and construction.

As the need for this type of housing stock is in higher demand
around the country, localities and states have sought to find ways to overcome
barriers and make ADUs a more widely available option. Fortunately, the growing
popularity means there is now a wide array of data, ordinances, and best
practices on record. NAHB will be publishing a new research report on smaller
homes, smaller lots, and ADUs later this spring.